The filter system for tertiary treatment of sewage effluent by land application - its performance in a subtropical environment

FILTER is an innovative, CSIRO developed system for treating effluent using high rate land application and subsequent effluent recapture via a closely spaced, subsurface drainage network. We report on the summer performance o f a FILTER system established in a subtropical environment on a relatively impermeable swelling clay soil underlain by a deep regional water table. Us ing secondary treated sewage effluent, the FILTER system produced effluent of tertiary nutrient standards (less than or equal to5 mg/L TN; less than o r equal to1 mg/L TP), with salinity levels suitable for subsequent irrigati on reuse (EC less than or equal to2.5 dS/m). Removal of faecal coliforms wa s considerably less effective. The hydraulic loading rate achieved was abou t two and a half times larger than conventional irrigation demand, but this was associated with high deep percolation losses (e 3 mm/day). Comparisons are made with the original FILTER system developed and tested by Jayawarda ne et al. in temperate Australia. Suggestions are made for modifications to , and further testing of FILTER in a subtropical environment.